Rocker cover bolts alloy heads and iron

[charvey]

Just putting the head back after doing some work on it, please check the depth of your rocker cover bolts they can bottom out in the thread or the thread is not long enough in the head which I found out by checking my alloy head.
I got two spare covers and checked each bolt for thread depth into the head without washers or gasket I had to cut the thread into the alloy head more in some cases carefully till each bolt tightened down the the cover and I was happy with it then put each bolt in the spare covers ready to fit and they don't get mixed up, there are lots of cracked alloy heads some for sale on ebay £500.00 and with cracked or missing side cases just where they bolt down and after this you can see why either stuff in the bottom of the threads or two longer bolt, two bolts are longer in each cover, anyway take care Clive

[Simon.Gardiner]

Hmmmmmmm...
All my (singles) rocker boxes have only ever had 1 longer bolt per rocker box (for the push-rod end of the box)....
I'm also quite keen on not undoing the bolts without making sure that the valves are fully closed (so no chance of ending up with the last bolt being levered by valve spring pressure).

SG

[paul.jameson]

Be especially careful of the early VCH / VHA alloy heads which have cycle thread rocker box bolts, just like the cast iron heads.

[nevhunter]

ALL heads have blind thread bosses and tend to get split/cracked by grunge in the bottom of the thread "hole", at times. Clean all of them out carefully. A small screwdriver usually works ok with compressed air to blow it out. With the "soft" alloy heads care with threads means avoid burrs and dirt and have a good fit of the thread and for both, have the correct length of bolt. Not too short and not too long and don't overtighten. Nev

[charvey]

Clive here
Yes two longer bolt with both covers, one on each rocker cover,The proof reader has been sacked even though it's near Christmas.

[Ian.Taylor]

My VHA had a hard life.ALL the rocker bolts were 3/8 course and not even the correct length.
About 4 years ago when one thread stripped I replaced most of the threads with timeserts. No way are they pulling out now.
And recently one head stud on the right side pull out, It was repaired with a Timsert.

[nevhunter]

IF the bolt stems were reduced in Diameter for some of it's length to prevent all the stretch being on the first few threads you wouldn't have so much of a problem. Very short studs like on the alloy twins and alloy fours are a disaster for pulling threads out. Most of those thread inserts are too bulky and weaken the casting.. Where studs are used a stepped stud might be better.. I make my own smaller section thread inserts of bronze or "better" alloy. Duralumin. (That's a trade name for a high strength aluminium alloy). It's time consuming and would cost a lot commercially. Nev